Research Area: Broad Challenge Area 11: Regenerative Medicine. Specific Challenge Topic: 11-HL-101* Develop cell-based therapies for cardiovascular, lung, and blood disease. We propose to build a new paradigm for advancing and transforming patient care through development of cell-based therapies for human lung disease. Analysis of acute lung injury in mice indicates that epithelial damage can prestage loss of alveolar structure and function. These data support the hypothesis that cell-based therapy focused on replacement of the damaged epithelium can ameliorate morbidity and mortality associated with high risk diagnosis and progression to acute lung injury. Our analysis of lung epithelial stem and facultative progenitor cells suggests that the latter cell type exhibits optimal characteristics for replacement of injured epithelial cells as well as restoration of critical homeostatic functions. Based on these studies we propose to use competitive repopulation to test the hypothesis that facultative progenitor cells can repopulate the injured airway or alveolar epithelium in the context of acute lung injury. These hypotheses will be tested using functionally distinct populations of human lung facultative progenitor cells, basal and the alveolar type II cells. These cell types are known to maintain and regenerate the normal bronchial and alveolar epithelial compartments. Acute and progressive aspects of acute lung injury will be represented using a novel mouse model that recapitulates the morbidity and mortality of acute lung injury on post-treatment days 5 and 10. Previously developed cell isolation methods and this unique mouse model will be combined to determine: 1) the characteristics of the most promising target patient population for cell-based therapy;2) the best cell type for treatment of early and late acute lung injury;and 3) preclinical parameters including optimal route, dose, and timing of treatment. Successful completion of this study will propel the field of cell replacement therapy for lung disease beyond the planning stage and into a position appropriate for initiation of clinical trials. The limitations of previous analyses will be overcome through implementation of an appropriately powered analysis of intersections between time, cell type, route, and dose. Trials for refinement of the treatment protocol and evaluation of consistency among donor cell populations are advanced components of the study design. Outcomes will be evaluated through quantitative measurements that are germane to pulmonary function. This novel intervention strategy has the potential to ameliorate morbidity and mortality in the almost 200,000 American citizens that suffer from acute lung injury associated with trauma, aspiration, or infection each year. Among these patients there are nearly 75,000 deaths per year. This benefit will be achieved through development of new treatment strategy and through facilitation of research focused on engineering approaches to lung regeneration or replacement. Thus, focused evaluation of the fundamental parameters highlighted in this pre-clinical trial will advance the emerging field of cell based therapy and regenerative medicine approaches to treatment of acute lung injury. PUBLIC HEALTH RELEVANCE: Knowledge gained through the proposed investigation has the potential to improve the health of patients with lung disease through development of a novel treatment strategy, through parallel improvements in our knowledge of endogenous lung epithelial reparative cells, and through provision of validated cell types to tissue engineers engaged in development of replacement tissue technology.